The present invention relates generally to color video signal dubbing systems, and more particularly to a dubbing system which reproduces the color video signal recorded on one magnetic medium and records the color video signals thus reproduced to another magnetic medium, without introducing degradation in the frequency characteristic linearity, pulse characteristic and the like, and furthermore accompanying no beat disturbances or reversal effect and the like.
Conventionally, a so-called low-band frequency conversion system is used as a system which records a color video signal onto a magnetic tape within a relatively narrow frequency band. In this system, the input color video signal is separated into a luminance signal and a carrier chrominance signal. The luminance signal is then frequency modulated, and the carrier chrominance signal undergoes frequency conversion to a frequency band lower than that of the frequency modulated luminance signal. Accordingly, these frequency modulated luminance signal and carrier chrominance signal converted to low-band are multiplexed and recorded on the magnetic tape.
When the color video signal recorded on one magnetic tape by the above procedure are to be dubbed onto another magnetic tape, the frequency modulated luminance signal and low-band frequency converted carrier chrominance signal, which are multiplexed and recorded on the magnetic tape, must first be reproduced by a magnetic reproducing apparatus. The frequency modulated luminance signal is separated from the multiplexed signal and frequency demodulated, while the low-band frequency converted carrier chrominance signal is frequency converted back into the original band. Hence, the reproduced color video signal is obtained by mixing the frequency demodulated luminance signal with the carrier chrominance signal which is frequency converted back into the original band. The reproduced color video signal thus obtained, is supplied to a magnetic recording apparatus, and by the identical signal processing procedure in the recording system as described above, the luminance signal is frequency modulated, the carrier chrominance signal undergoes frequency conversion into a band lower than that of the frequency modulated luminance signal, and the multiplexed signal of the above two signals is recorded onto the other magnetic tape.
Accordingly, the color video signal is recorded onto one magnetic tape through the recording system of the magnetic recording apparatus. Upon dubbing, the signal is reproduced from the magnetic tape by the magnetic reproducing apparatus and undergoes signal processing by passing through the reproducing system of the magnetic reproducing apparatus, and is supplied to the magnetic recording apparatus and recorded onto another magnetic tape after undergoing the identical signal processing procedure as that performed by the above recording system upon the above recording on one magnetic tape.
Hence, according to the above conventional dubbing system, the signal which is to be reproduced from one magnetic tape and dubbed on another magnetic tape must pass through a frequency demodulator, a frequency modulator, frequency converters and the like. Therefore, degradation is introduced in the frequency characteristic, pulse characteristic, linearity and the like, and furthermore resulting in the introduction of degradation in the picture quality due to the effect by the beat interference, and in extreme cases, disadvantageous in that reversal effect in the picture screen is introduced.